MONDO_0009069 (congenital lactic acidosis, Saguenay-Lac-Saint-Jean type) is saguenay-Lac-St. Jean (SLSJ) type congenital lactic acidosis, a French Canadian form of Leigh syndrome, is a mitochondrial disease characterized by chronic metabolic acidosis, hypotonia, facial dysmorphism and delayed development. Also known as: COX deficiency, French-Canadian type, Leigh syndrome, French-Canadian type, Leigh syndrome, Saguenay-Lac-Saint-Jean type, SLSJ-COX deficiency, cytochrome C oxidase deficiency, French-Canadian type, cytochrome oxidase deficiency, Saguenay-Lac-Saint-Jean type, mitochondrial complex IV deficiency, nuclear type 5, (French-Canadian).